|Número de publicación||US3583786 A|
|Tipo de publicación||Concesión|
|Fecha de publicación||8 Jun 1971|
|Fecha de presentación||23 Sep 1969|
|Fecha de prioridad||23 Sep 1969|
|Número de publicación||US 3583786 A, US 3583786A, US-A-3583786, US3583786 A, US3583786A|
|Inventores||Marcatili Enrique A J|
|Cesionario original||Bell Telephone Labor Inc|
|Exportar cita||BiBTeX, EndNote, RefMan|
|Citas de patentes (2), Citada por (32), Clasificaciones (11), Eventos legales (1)|
|Enlaces externos: USPTO, Cesión de USPTO, Espacenet|
United States Patent Inventor Appl. No.
Filed Patented Assignee Enrique A. J. Marcatiii Rumson, NJ.
Sept. 23, 1969 June 8, 1971 Bell Telephone Laboratories, Incorporated Murray Hill, Berkeley Heights, NJ.
OPTICAL WAVEGUIDE FORMED OF CYLINDERS WITH OP'IICALLY SMOOTH INTERFACES THEREBETWEEN i 6 Claims,4 Drawing Figs.
u.s. Cl... 350/96WG Int. Cl G02b 5/14 Field of Search 350/96, 96
 References Cited UNITED STATES PATENTS 3,386,043 5/1968 Marcatiii et al 350/96WGUX 3,436,141 4/1969 Comte 350/96 Primary Examiner-John K. Corbin v Attorneys-R. J. Guenther and Arthur J. Torsiglieri ABSTRACT: Some practical problems encountered in the fabrication of hollow metallic waveguides for use at millimeter and optical frequencies are overcome in a structure comprising a hollow glass tube surrounded by pairs of dielectric layers of prescribed refractive indices and thicknesses. An outer metallic layer is optional. In addition to resolving fabrication problems, the attenuation constant is reduced as the number of pairs of dielectric layers is increased.
OPTICAL WAVEGUIDE FORMED OF CYLINDERS WITH OPTIC ALLY SMOOTH INTERFACES THEREBETWEEN This invention relates to dielectric waveguiding structures whose cross-sectional dimensions are large compared to the wavelength of the electromagnetic wave energy to be propagated therethrough.
BACKGROUND OF THE INVENTION In U.S. Pat. No. 3,386,043, there is disclosed a dielectric waveguide comprising an inner, low-loss dielectric material, such as air, surrounded by an outer, dielectric material of substantially higher dielectric constant. In particular, it was noted that the outer dielectric material can be a metal since, at optical frequencies, for which the invention was of particular interest, metals exhibit large dielectric constants. As a practical matter, however, it has been found to be extremely difficult to produce a sufficiently smooth hollow metallic tube whose inside diameter is of the order of 10 wavelengths at the frequencies of interest. To avoid this difficulty, the inner surface of glass tubes, having the required internal cross-sectional dimension, have been coated with a metallic layer. The resulting surface, however, has been found to be spongy, resulting in high attenuation due to scattering at the air-metal interface.
SUMMARY OF THE INVENTION In accordance with the present invention, the prior art waveguide has been modified by depositing a metallic layer on the outer surface of a hollow glass tube to form a three-layer dielectric waveguide comprising an inner dielectric material, surrounded by a second dielectric material of slightly higher dielectric constant, and an outer, usually metallic layer of substantially higher dielectric constant. By depositing the metallic layer on the outer surface of the glass tube, instead of its inner surface, a smoother metallic interface is obtained.
In a second embodiment of the invention a plurality of pairs of layers of dielectric materials of prescribed refractive indices and thicknesses are interposed between the glass and the outer metallic layer, resulting in a reduction in the attenuation constant of the waveguide. By making the number of pairs of layers large enough, the outer metallic layer can be omitted.
These and other objects and advantages of the present invention, and its various features will appear more fully upon consideration of the several illustrative embodiments now to be described in detail in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a long distance transmission system utilizing the present invention;
FIG. 2 shows a first embodiment of the invention comprising three dielectric materials;
FIG. 3 shows a second embodiment of the invention in which a plurality of pairs of layers of dielectric materials are placed between the outer two layers of material of the embodiment of FIG. 2; and
FIG. 4 shows an alternate arrangement of the embodiment of FIG. 3 in which the outermost dielectric layer is omitted.
DETAILED DESCRIPTION Referring to FIG. 1, there is illustrated a typical longdistance, guided wave transmission system in which the present invention has utility. The system is characterized as long so as to define a system in which the factor of transmission attenuation is important. The length of such a system would be measured in hundreds of meters or miles.
The system comprises a source, 10, of millimeter or optical wave energy, which source can be a transmitter, or if this is an intermediate station, a repeater. Source 10 is connected by means of a dielectric transmission line 11 to a load 12, which can be either the terminal end of the system or another repeater.
The transmission line is further characterized as having cross-sectional dimensions that are large compared to the wavelength of the wave energy propagating therein. For millimeter waves, cross-sectional dimensions of the order of 10 or more wavelengths are typical. For optical waves, cross-sectional dimensions of the order of hundreds of wavelengths are typical.
FIG. 2 is a detailed drawing of line 11. The latter comprises a first, inner dielectric cylinder 20 of radius r and refractive index in, surrounded by a second, hollow dielectric cylinder. 21 of thickness t and refractive index ri and a third, outer hollow dielectric cylinder 22 of refractive index n,.
The inner cylinder 20, within which most of the wave energy is confined, is preferably composed of an inert gas, such as nitrogen, or this region can be evacuated in order to minimize losses. Cylinder 20 can, alternatively, be a low-loss solid or liquid dielectric material.
The second cylinder 21 is similarly a low-loss material whose refractive index n and optimum thickness are related by )t is the free-space wavelength of the wave energy,
A, is the radial wavelength of the guided mode in cylinder 21, and
m is an integer.
The thickness is not critical, however, and may deviate from this optimum value by as much mil/8A,.
The outer cylinder, as described in the above-identified patent, is advantageously a high dielectric loss material for the reasons described therein.
A typical waveguide, in accordance with the present invention, would comprise a hollow glass tube upon whose outer surface a layer of metal has been deposited. In such a structure, the inner cylinder is air, the second dielectric material is the glass, and the third dielectric material is the metal. The practical advantage of such an arrangement resides in the fact that the metal is deposited upon a smooth glass surface, forming a correspondingly smooth interface which has negligible scattering losses.
FIG. 3 shows a second embodiment of the invention wherein a plurality of additional pairs of layers of low-loss dielectric materials are interposed between the outer two dielectric cylinders of the waveguide shown in FIG. 2. Using the same identification numerals in FIG. 3 for the corresponding elements of the waveguide, the plurality of pairs of layers 30-30, 3l3l'--and q-q' are interposed between cylinder 21 and the outermost cylinder 22. In particular, it has been discovered that when the layer thicknesses T and T, are
k and j are integers;
q is the number of pairs of dielectric layers;
). is the free space wavelength of the guided wave energy;
a, is the attenuation constant of the waveguide withoutany pairs of layers of dielectric materials; and
A, and A, are the radial wavelengths of the guided mode in the respective layers ofdielectric material.
In the particular case where all the pairs of layers are identical, equation (4) reduces to As an example of the reduction in the attenuation that can be realized by this technique, consider a waveguide comprising 20 pairs of layers made of MgF having a refractive index of 1.38 at A=O.5 a, and ZnS, having a refractive index of 2.35. Substituting these values in equation (5) gives a=(0. l 96) a Thus, the losses in a waveguide made in accordance with the second embodiment of the invention are roughly onethousandth the losses of both a prior art waveguide and a waveguide made in accordance with FIG. 2.
it should also be noted that while the thicknesses T, and T given by equations (2) and (3) are optimum, they are not critical and can vary by as much as fl /8 andzl: l v/8, respectively. The full reduction in attenuation, given by equation (4) will not be realized, however, if the thicknesses are other than optimum.
FIG. 4 shows a modification of the embodiment of FIG. 3 wherein the number q of pairs of dielectric layers is sufficiently large, of the order of or more, to permit omitting the outer dielectric layer 22. An analysis of this configuration shows that the added attenuation which results when outer layer 22 is omitted is slight compared to the overall reduction in attenuation that is realized when the number of pairs of layers is sufficiently large.
1. A transmission medium for guiding electromagnetic wave energy comprising a plurality of concentric cylinders includmg:
an innermost cylinder of low-loss material having a refractive index n,;
a second cylinder of low-loss material having a refractive index n greater than n and a thickness surrounding said innermost cylinder; where m is an integer forming optically smooth interfaces characterized in that:
each of said pairs of layers includes an inner layer of material having a refractive index n,, and a thickness t,,=(2k+l),,/4i,,/8, and an outer layer of material having a refractive index p and a thickness =(2 j W/ iv/ where k and j are integers;
4. The transmission medium according to claim 3 wherein said q pairs of layers are different.
5. The transmission medium according to claim 3 wherein said 'q pairs of layers are the same.
6. A transmission medium for guiding electromagnetic wave energy comprising:
an innermost cylinder of low-loss material having a refractive index m; g a second cylinder of low-loss material having a refractive index n: greater than n; and a thickness ra n 2 8 surrounding said innermost cylinder; where m is an integer;
and A is the free space wavelength of said wave energy; and a plurality of q pairs of layers of low-loss material surrounding said second cylinder; characterized in that:
each of said pairs of layers includes an inner layer of material having refractive index n, and a thickness M T, (2k-l 1) 4 8 and an outer layer of material having a refractive index n I and a thickness where k and j are integers 1 and
|Patente citada||Fecha de presentación||Fecha de publicación||Solicitante||Título|
|US3386043 *||31 Jul 1964||28 May 1968||Bell Telephone Labor Inc||Dielectric waveguide, maser amplifier and oscillator|
|US3436141 *||25 Feb 1965||1 Abr 1969||Comp Generale Electricite||Hollow wave guide with selectively reflecting inner face|
|Patente citante||Fecha de presentación||Fecha de publicación||Solicitante||Título|
|US3973828 *||4 Jun 1974||10 Ago 1976||Hitachi, Ltd.||Optical wave guide|
|US4000416 *||11 Jul 1975||28 Dic 1976||International Telephone And Telegraph Corporation||Multi-core optical communications fiber|
|US4068920 *||20 Ago 1976||17 Ene 1978||University Of Southern California||Flexible wave guide for laser light transmission|
|US4082420 *||14 Ene 1976||4 Abr 1978||Sumitomo Electric Industries, Ltd.||An optical transmission fiber containing fluorine|
|US4260220 *||15 Jun 1979||7 Abr 1981||Canadian Patents And Development Limited||Prism light guide having surfaces which are in octature|
|US4453803 *||26 Abr 1982||12 Jun 1984||Agency Of Industrial Science & Technology||Optical waveguide for middle infrared band|
|US4630885 *||2 Mar 1984||23 Dic 1986||Northrop Corporation||Multichannel optical wave guide resonator|
|US4768858 *||8 Jul 1985||6 Sep 1988||Trimedyne, Inc.||Hollow fiberoptic|
|US4770544 *||8 May 1987||13 Sep 1988||General Electric Company||Temperature sensor|
|US4805984 *||5 Sep 1986||21 Feb 1989||Minnesota Mining And Manufacturing Company||Totally internally reflecting light conduit|
|US4806289 *||16 Ene 1987||21 Feb 1989||The Dow Chemical Company||Method of making a hollow light pipe|
|US4826274 *||21 Dic 1987||2 May 1989||Motorola, Inc.||Optical coupling arrangements including emitter and detector placed inside of a hollow closed end reflective waveguide|
|US4911712 *||14 Abr 1988||27 Mar 1990||Heraeus Lasersonics, Inc.||Medical laser probe|
|US4932749 *||17 Mar 1989||12 Jun 1990||L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes George Claude||Optical waveguides formed from multiple layers|
|US4941074 *||29 Dic 1988||10 Jul 1990||Road Rescue, Inc.||Light boxes|
|US5030217 *||14 Sep 1989||9 Jul 1991||Heraeus Lasersonics, Inc.||Medical laser probe and method of delivering CO2 radiation|
|US5043850 *||10 Ene 1990||27 Ago 1991||Minnesota Mining And Manufacturing Company||Direction dependent line light source|
|US5188634 *||13 Jul 1990||23 Feb 1993||Trimedyne, Inc.||Rotatable laser probe with beveled tip|
|US5243618 *||22 Nov 1991||7 Sep 1993||Hughes Aircraft Company||Cavity resonator incorporating waveguide filter|
|US5276761 *||16 Sep 1991||4 Ene 1994||Ebara Corporation||Hollow waveguide for ultraviolet wavelength region laser beams|
|US5394501 *||13 Oct 1993||28 Feb 1995||Coherent, Inc.||Optical coating for reflecting visible and longer wavelength radiation having grazing incidence angle|
|US5461692 *||30 Nov 1993||24 Oct 1995||Amoco Corporation||Multimode optical fiber coupling apparatus and method of transmitting laser radiation using same|
|US7450808||8 Jul 2005||11 Nov 2008||Nuffern||Optical fiber article and methods of making|
|US7658514 *||11 Dic 2006||9 Feb 2010||Lg Electronics Inc.||Light guide, method and apparatus for manufacturing the same, and illuminating system having the same|
|US8516856 *||6 Dic 2005||27 Ago 2013||Massachusetts Institute Of Technology||Methods of making fiber waveguides from multilayer structures|
|US8769995 *||25 Jul 2006||8 Jul 2014||Weatherford/Lamb, Inc.||Method for making large diameter multicore optical waveguide|
|US20030205065 *||6 May 2002||6 Nov 2003||Yuji Matsuura||Method for making hollow glass optical waveguide|
|US20060201206 *||6 Dic 2005||14 Sep 2006||Gilles Benoit||Fiber waveguides and methods of making the same|
|US20070009217 *||8 Jul 2005||11 Ene 2007||Martin Seifert||Optical fiber article and methods of making|
|US20070028651 *||25 Jul 2006||8 Feb 2007||Dowd Edward M||Method for making large diameter optical waveguide having a bragg grating and being configured for reducing the bulk modulus of compressibility thereof|
|US20070242473 *||11 Dic 2006||18 Oct 2007||Lg Electronics Inc.||Light guide, method and apparatus for manufacturing the same, and illuminating system having the same|
|US20130195466 *||16 Ene 2013||1 Ago 2013||Sony Corporation||Transmission method and transmission system|
|Clasificación de EE.UU.||385/125, 65/393, 385/127|
|Clasificación internacional||G02B6/02, H01P3/00, H01P3/18, G02B6/032|
|Clasificación cooperativa||H01P3/18, G02B6/032|
|Clasificación europea||G02B6/032, H01P3/18|
|11 Oct 1983||AS||Assignment|
Owner name: BELL & HOWELL COMPANY A DE CORP.
Free format text: MERGER;ASSIGNORS:BELL & HOWELL COMPANY, AN ILL CORP. (MERGED INTO);DELAWARE BELL & HOWELL COMPANY, A DE CORP. (CHANGED TO);REEL/FRAME:004195/0168
Effective date: 19830907